Reusable mass-sensor in manufacture of organic light-emitting devices

ABSTRACT

A method for controlling the deposition of an organic layer in making an organic light-emitting device includes depositing at a deposition zone organic material forming a layer of the organic light-emitting device and providing a movable sensor which, when moved into the deposition zone and is being coated during the depositing step, provides a signal representing the deposition rate and thickness of the organic material forming the layer. The method also includes controlling the deposition of the organic material in response to the signal to control the deposition rate and thickness of the deposited organic material forming the layer, moving the movable sensor from the deposition zone to a cleaning position, and removing organic material from the movable sensor to permit reuse of the movable sensor.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] Reference is made to commonly assigned U.S. patent applicationSer. No. ______ filed concurrently herewith entitled “Controlling theThickness of an Organic Layer in an Organic Light-Emitting Device” bySteven A. Van Slyke et al., the disclosure of which is incorporatedherein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to monitoring andcontrolling formation of organic layers by physical vapor deposition inmaking organic light-emitting devices.

BACKGROUND OF THE INVENTION

[0003] An organic light-emitting device, also referred to as an organicelectroluminescent device, can be constructed by sandwiching two or moreorganic layers between first and second electrodes.

[0004] In a passive matrix organic light-emitting device of conventionalconstruction, a plurality of laterally spaced light-transmissive anodes,for example indium-tin-oxide (ITO) anodes are formed as first electrodeson a light-transmissive substrate such as, for example, a glasssubstrate. Two or more organic layers are then formed successively byvapor deposition of respective organic materials from respectivesources, within a chamber held at reduced pressure, typically less than10⁻³ Torr. A plurality of laterally spaced cathodes are deposited assecond electrodes over an uppermost one of the organic layers. Thecathodes are oriented at an angle, typically at a right angle, withrespect to the anodes.

[0005] Such conventional passive matrix organic light-emitting devicesare operated by applying an electrical potential (also referred to as adrive voltage) between appropriate columns (anodes) and, sequentially,each row (cathode). When a cathode is biased negatively with respect toan anode, light is emitted from a pixel defined by an overlap area ofthe cathode and the anode, and emitted light reaches an observer throughthe anode and the substrate.

[0006] In an active matrix organic light-emitting device, an array ofanodes are provided as first electrodes by thin-film transistors (TFTs)which are connected to a respective light-transmissive portion. Two ormore organic layers are formed successively by vapor deposition in amanner substantially equivalent to the construction of theaforementioned passive matrix device. A common cathode is deposited as asecond electrode over an uppermost one of the organic layers. Theconstruction and function of an active matrix organic light-emittingdevice is described in U.S. Pat. No. 5,550,066, the disclosure of whichis herein incorporated by reference.

[0007] Organic materials, thicknesses of vapor-deposited organic layers,and layer configurations, useful in constructing an organiclight-emitting device, are described, for example, in U.S. Pat. Nos.4,356,429; 4,539,507; 4,720,432; and 4,769,292, the disclosures of whichare herein incorporated by reference.

[0008] In order to provide an organic light-emitting device which issubstantially uniform and of precise thickness, the formation of organiclayers of the device has to be monitored or controlled. Such control ofvapor deposition of organic layers by sublimation or evaporation oforganic material from a source is typically achieved by positioning amonitor device within the same vapor deposition zone in which thesubstrate or structure is to be coated with the organic layer. Thus, themonitor device receives an organic layer at the same time as the organiclayer is being formed on the substrate or structure. The monitor device,in turn, provides an electrical signal which is responsive to a rate atwhich the organic layer is being formed on the monitor device and,therefore, related to a rate at which the organic layer is being formedon the substrate or structure which will provide the organiclight-emitting device. The electrical signal of the monitor device isprocessed and/or amplified, and is used to control the rate of vapordeposition and the thickness of the organic layer being formed on thedevice substrate or structure by adjusting a vapor source temperaturecontrol element, such as, for example, a source heater.

[0009] Well known monitor devices are so-called crystal mass-sensordevices in which the monitor is a quartz crystal having two opposingelectrodes. The crystal is part of an oscillator circuit provided in adeposition rate monitor. Within an acceptable range, a frequency ofoscillation of the oscillator circuit is approximately inverselyproportional to a mass-loading on a surface of the crystal occasioned bya layer or by multiple layers of material deposited on the crystal. Whenthe acceptable range of mass-loading of the crystal is exceeded, forexample by build-up of an excess number of deposited layers, theoscillator circuit can no longer function reliably, necessitatingreplacement of the “overloaded” crystal with a new crystal mass-sensor.Such replacement, in turn, requires discontinuation of the vapordeposition process.

[0010] In addition, when certain types of organic layers are depositedonto crystal mass-sensor devices there can be a tendency for the layersto start cracking and flaking from the mass-sensor surface after coatingthickness build-up on the order of 500-2,000 nanometer (nm). This cancause the crystal mass-sensor to become inaccurate in its coating ratemeasurement capability at thicknesses well below the aforementionedmass-loading limit.

[0011] In development efforts, several organic light-emitting devicescan typically be prepared before a crystal mass-sensor must be replaceddue to excessive mass-loading or cracking and flacking of a depositedfilm. This does not present a problem in such efforts, since otherconsiderations usually require disruption of vapor deposition by openingthe deposition chamber for manual replacement of substrates orstructures, replenishment of organic material in relatively small vaporsources, and the like.

[0012] However, in a manufacturing environment, designed for repeatedlymaking a relatively large number of organic light-emitting devices,replacement of “overloaded” crystal mass-sensors or cracked and flakingorganic coatings on crystal mass-sensors would constitute a seriouslimitation because a manufacturing system is configured in all aspectsto provide the capacity of producing all organic layers on numerousdevice structures and, indeed, to produce fully encapsulated organiclight-emitting devices.

SUMMARY OF THE INVENTION

[0013] It is, therefore, an object of the present invention to form anorganic layer by providing a reusable sensor for controlling thethickness of such layer. This object is achieved in a method fordepositing an evaporated or sublimed organic layer onto a structurewhich will form part of an organic light-emitting device, comprising thesteps of:

[0014] a) depositing at a deposition zone organic material forming alayer of the organic light-emitting device;

[0015] b) providing a movable sensor which, when moved into thedeposition zone and is being coated during the depositing step, providesa signal representing the thickness of the organic material forming thelayer;

[0016] c) controlling the deposition of the organic material in responseto the signal to control a deposition rate and thickness of the organiclayer formed on the structure;

[0017] d) moving the movable sensor from the deposition zone to acleaning position; and

[0018] e) removing organic material from the movable sensor to permitreuse of the movable sensor.

[0019] It is an advantage of the present invention that crystalmass-sensors which control the thickness of one or more organic layersin a light-emitting device can be cleaned and reused thereby providing amore efficient manufacturing process.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a schematic perspective view of a passive matrix organiclight-emitting device having partially peeled-back elements to revealvarious layers;

[0021]FIG. 2 is a schematic perspective view of a manufacturing systemsuitable for manufacture of a relatively large number of organiclight-emitting devices (OLEDs) and having a plurality of stationsextending from hubs;

[0022]FIG. 3 is a schematic section view of a carrier containing arelatively large number of substrates or structures, and positioned in aload station of the system of FIG. 2 as indicated by section lines 3-3in FIG. 2;

[0023]FIG. 4 is a schematic section view of a vapor deposition stationdedicated to forming vapor deposited organic hole-transporting layers(HTL) on a substrate or structure in the system of FIG. 2 as indicatedby section lines 4-4 in FIG. 2;

[0024]FIG. 5 is an enlarged schematic section view of a crystalmass-sensor shown in FIG. 4 and associated deposition rate monitor;

[0025]FIG. 6 shows schematically the sensor of FIG. 4 having formed onone surface a relatively high mass-loading in the form of a number N oflayers of organic hole-transporting material wherein such mass-loadingof a prior art sensor would cause the associated deposition rate monitorto become unreliable in its reading of deposition rate, or to becomeinoperative;

[0026]FIG. 7 shows schematically, positioned within the HTL depositionstation of FIG. 2, a movable sensor assembly in accordance with theinvention in which a first crystal mass-sensor is operative in adeposition zone while a third sensor is shown positioned proximate alight guide for providing a cleaning flash, with a second sensordepicted after cleaning and in a position to advance into the depositionzone as the first sensor accumulates a relatively high mass-loading;

[0027]FIG. 7A shows the light guide of FIG. 7 which further includes anoptional heater positioned adjacent the tip of the light guide and anoptional trap for collecting organic material removed from the sensor bya cleaning flash;

[0028]FIG. 7B shows schematically the light guide directed obliquelytowards the mass-loaded sensor and an optional trap for collectingorganic material removed from the sensor by a cleaning flash;

[0029]FIG. 7C shows schematically an alternative optical cleaningconfiguration for removing organic material from a sensor in which acleaning radiation source provides cleaning radiation directed towards amass-loaded sensor via lenses, a window positioned in the chamberhousing, and an optionally heatable mirror;

[0030]FIG. 8 is a view of the movable sensor assembly of FIG. 7 butshowing schematically a heater for cleaning the sensor having the highmass-loading in accordance with the invention;

[0031] FIGS. 9A-9D are schematic plan views of different embodiments ofrotatable sensor supports useful in the practice of the invention, withpositions of sensors in the deposition zone and sensor cleaningpositions indicated in dashed outlines; and

[0032]FIG. 10 is an enlarged section view of the crystal mass-sensorshown in FIG. 5, but having a radiation-absorbing layer preformed overthe sensor surface for enhancing removal in whole or in part of theorganic layers on the sensor in the cleaning position, in accordancewith the invention.

[0033] The drawings are necessarily of a schematic nature since layerthickness dimensions of OLEDs are frequently in the sub-micrometerranges, while features representing lateral device dimensions can be ina range of 50-500 millimeter. Accordingly, the drawings are scaled forease of visualization rather than for dimensional accuracy.

[0034] The term “substrate” denotes a light-transmissive support havinga plurality of laterally spaced first electrodes (anodes) preformedthereon, such substrate being a precursor of a passive matrix OLED. Theterm “structure” is used to describe the substrate once it has receiveda portion of a vapor deposited organic layer, and to denote an activematrix array as a distinction over a passive matrix precursor.

DETAILED DESCRIPTION OF THE INVENTION

[0035] Turning to FIG. 1, a schematic perspective view of a passivematrix organic light-emitting device (OLED) 10 is shown having partiallypeeled-back elements to reveal various layers.

[0036] A light-transmissive substrate 11 has formed thereon a pluralityof laterally spaced first electrodes 12 (also referred to as anodes). Anorganic hole-transporting layer (HTL) 13, an organic light-emittinglayer (LEL) 14, and an organic electron-transporting layer (ETL) 15 areformed in sequence by a physical vapor deposition, as will be describedin more detail hereinafter. A plurality of laterally spaced secondelectrodes 16 (also referred to as cathodes) are formed over the organicelectron-transporting layer 15, and in a direction substantiallyperpendicular to the first electrodes 12. An encapsulation or cover 18seals environmentally sensitive portions of the structure, therebyproviding a completed OLED 10.

[0037] Turning to FIG. 2, a schematic perspective view of amanufacturing system 100 is shown which is suitable for manufacture of arelatively large number of organic light-emitting devices usingautomated or robotic means (not shown) for transporting or transferringsubstrates or structures among a plurality of stations extending from abuffer hub 102 and from a transfer hub 104. A vacuum pump 106 via apumping port 107 provides reduced pressure within the hubs 102, 104, andwithin each of the stations extending from these hubs. A pressure gauge108 indicates the reduced pressure within the system 100. The pressurecan be in a range from about 10⁻² to 10⁻⁶ Torr.

[0038] The stations include a load station 110 for providing a load ofsubstrates or structures, a vapor deposition station 130 dedicated toforming organic hole-transporting layers (HTL), a vapor depositionstation 140 dedicated to forming organic light-emitting layers (LEL), avapor deposition station 150 dedicated to forming organicelectron-transporting layers (ETL), a vapor deposition station 160dedicated to forming the plurality of second electrodes (cathodes), anunload station 103 for transferring structures from the buffer hub 102to the transfer hub 104 which, in turn, provides a storage station 170,and an encapsulation station 180 connected to the hub 104 via aconnector port 105. Each of these stations has an open port extendinginto the hubs 102 and 104, respectively, and each station has avacuum-sealed access port (not shown) to provide access to a station forcleaning, replenishing materials, and for replacement or repair ofparts. Each station includes a housing which defines a chamber.

[0039]FIG. 3 is a schematic section view of the load station 110, takenalong section lines 3-3 of FIG. 2. The load station 110 has a housing110H which defines a chamber 110C. Within the chamber is positioned acarrier 111 designed to carry a plurality of substrates 11 havingpreformed first electrodes 12 (see FIG. 1). An alternative carrier 111can be provided for supporting a plurality of active matrix structures.Carriers 111 can also be provided in the unload station 103 and in thestorage station 170.

[0040] Turning to FIG. 4, a schematic cross section view of the HTLvapor deposition station 130 is shown, taken along the section lines 4-4of FIG. 2. A housing 130H defines a chamber 130C. A substrate 11 (seeFIG. 1) is held in a holder 131 which can be constructed as a maskframe. A source 134 is positioned on a thermally insulative support 132,the source 134 filled with a supply of organic hole-transportingmaterial 13 a to a level 13 b. The source 134 is heated by heatingelements 135 which are connected via leads 245 and 247 to correspondingoutput terminals 244 and 246 of a source power supply 240.

[0041] When a source temperature is sufficiently elevated, the organichole-transporting material 13 a will evaporate or sublime and thusprovide a deposition zone 13 v of vapor of organic hole-transportingmaterial, indicated schematically by dashed lines and arrows.

[0042] The substrate 11 as well as a conventional crystal mass-sensor200 are positioned within the deposition zone, and each of theseelements has an organic hole-transporting layer being formed thereon asindicated by the designation 13 f, shown in dashed outline.

[0043] As is well known in the art, the crystal mass-sensor 200 isconnected via a lead 210 to an input terminal 216 of a deposition ratemonitor 220. The sensor 200 is part of an oscillator circuit provided inthe monitor 220 and the circuit oscillates at a frequency which isapproximately inversely proportional to a mass-loading of the crystalsuch as by a mass-loading provided by the layer 13 f being formed. Themonitor 220 includes a differentiating circuit which generates a signalproportional to a rate of mass-loading, i.e. proportional to a rate ofdeposition of the layer 13 f. This signal is indicated by the depositionrate monitor 220, and is provided at an output terminal 222 thereof. Alead 224 connects this signal to an input terminal 226 of a controlleror amplifier 230 which provides an output signal at an output terminal232. The latter output signal becomes an input signal to the sourcepower supply 240 via lead 234 and input terminal 236.

[0044] Thus, if the vapor stream within the vapor deposition zone 13 vis temporally stable, the mass build-up or growth of the layer 13 f willproceed at a constant rate. The rate monitor 220 will provide a constantsignal at output terminal 222, and the source power supply 240 willprovide a constant current to the heating elements 135 of the source 134via the leads 245 and 247, thereby maintaining the temporally stablevapor stream within the deposition zone. Under stable vapor depositionconditions, i.e. conditions of a constant deposition rate, a desiredfinal thickness of an organic hole-transporting layer 13 (see FIG. 1) isachieved on the structure and on the crystal mass-sensor 200 during afixed deposition duration, at which time the vapor deposition isterminated by terminating the heating of the source 134, or bypositioning a shutter (not shown) over the source.

[0045] While a relatively simple source 134 is shown in FIG. 4 forillustrative purposes, it will be appreciated that numerous other sourceconfigurations can be effectively used to provide evaporated or sublimedvapors of organic materials within a deposition zone. Particularlyuseful sources are extended or linear physical vapor deposition sourcesdisclosed by R. G. Spahn in U.S. patent application Ser. No. 09/518,600,filed Mar. 3, 2000, and commonly assigned.

[0046]FIG. 5 is an enlarged schematic section view of the prior artcrystal mass-sensor 200 shown in FIG. 4, together with the associateddeposition rate monitor 220. The crystal 204 has a front electrode 205and a rear electrode 206. An electrically grounded casing 202 is inelectrical contact with the front electrode 205 and via a connection 209to a shielded portion of the lead 210. The oscillator-signal-carryingportion of lead 210 is connected to the rear electrode 206 by aconnector 207. Portions of the housing 130H, the vapor deposition zone13 v, and the organic hole-transporting layer 13 f being formed on thefront electrode 205 and front portions of the casing 202 correspond tothe respective elements of FIG. 4.

[0047] Generally, the casing 202 of the crystal mass-sensor is watercooled (not shown in the drawings). The water cooling maintains a stablecrystal temperature and ensures that the deposition monitoring isaccurate and uninfluenced by thermal effects.

[0048]FIG. 6 shows schematically the crystal mass-sensor 200 of FIG. 4now having a relatively high mass-loading in the form of a number N oflayers of organic hole-transporting material 13. At such relatively highmass-loading (due to cumulative deposition of layers as N substrates orstructures in succession received an organic hole-transporting layer 13)the deposition rate monitor 220 may become inoperative or becomeunreliable in its reading of a deposition rate.

[0049] The monitor 220 may also become unreliable due to cracking,peeling or flaking of portions of the organic material deposited on thesensor at thicknesses lower than a thickness corresponding to Nsuccessive layers.

[0050] Turning now to FIG. 7, there is shown one embodiment of amass-sensor assembly 300 in accordance with the present invention,replacing the single fixedly positioned mass-sensor 200 shown in FIGS.4, 5, and 6.

[0051] A rotatably movable sensor support 320 is depicted forillustrative purposes as supporting three crystal mass-sensors 301, 302,and 303. Sensor 301 is positioned and operative in the vapor depositionzone 13 v (together with a substrate or structure as shown in FIG. 4) asdescribed previously. A lead is connected to a rear electrode of eachcrystal (see FIG. 5) and a lead contact 323 (such as, for example, aspring-biased contact) engages a sensor contact 321 (of sensor 301)formed on the electrically insulative sensor support 320.

[0052] The sensor support 320 is rotatably disposed in the housing 130Hof the station 130 (see FIG. 2) via a seal 327, and can be rotated by arotator 325 in a manual mode as depicted here, or in an automatedindexed rotation mode via a stepper motor or the like.

[0053] While the sensor 301 is operative in the deposition zone, asensor 303 is shown positioned proximate a light guide 392 which willprovide from a cleaning flash unit 390 a flash of radiation sufficientlypowerful to remove the multi-layer mass-loading 13 (xN) from this sensor303 by heat-induced sublimation or evaporation, or to remove an organicdeposit which may be partially cracked, peeled or flaked at reducedmass-loading. Such cleaning or removal of organic material from sensor303 is effected by sublimation or evaporation in a manner substantiallyequivalent to formation of organic vapors in the vapor deposition zone13 v by sublimation or by evaporation of organic material 13 a from thesource 134. The flash of radiation provided by cleaning flash unit 390is of a magnitude sufficient to raise the temperature of the organicmaterial deposited on the sensor to a temperature sufficient to initiatesublimation or evaporation of the organic material, but remain below thetemperature required to remove the metal electrode on the sensor 303 orto adversely effect the performance of the sensor 303. Organic materialsuseful for organic light emitting devices are particularly amenable tothis technique because these materials are vaporized at temperaturessignificantly below the temperatures required to vaporize most inorganicmaterials such as the electrode materials commonly used for crystal masssensors. Once the sensor 303 is cleaned, it can be then positioned inthe deposition zone 13 v and be utilized again for monitoring thedeposition rate and thickness of the organic layer without opening thedeposition chamber 130C and thereby releasing the vacuum.

[0054] A sensor 302 is shown after cleaning, and in a position on thesensor support to advance into the deposition zone as the sensor 301accumulates an undesirably high mass-loading.

[0055] A shield 329 is positioned to provide vapor deposition onto onesensor in the deposition zone, and to protect other sensors from vapordeposition.

[0056] It will be appreciated that the light guide 392 is coupledthrough the housing 130H via a vacuum-sealed feed-through (not shown).Similarly, all electrical leads enter or exit the chamber 130C throughthe housing 130 via a corresponding electrical feed-through. Suchfeed-through elements are well known in the art of vacuum systemstechnology.

[0057] The light guide 392 can be an optical fiber cable constructed ofa material which transmits light provided by the cleaning flash unit390. Alternatively, the light guide 392 can be constructed as a hollowor tubular light-transmissive element.

[0058] In FIG. 7A, the light guide 392 includes an optional heater 392Hpositioned adjacent to the tip, or at the tip, of the light guide, andan optional trap 392T. The purpose of the heater 392H is to heat theoptically active tip area of the light guide 392 so that organicsublimate (removed organic material) vaporized from the surface of thesensor 303 is prevented from depositing on the tip area of the lightguide. The trap 392 is used to collect the sublimate and inhibitspreading of such sublimate throughout the chamber 130C. The trap 392Tmay be cooled to enhance condensation of the organic sublimate withinthe trap.

[0059]FIG. 7B shows a light guide 392B in a configuration which candirect light from the cleaning flash unit 390 under an oblique angletowards the mass-loaded sensor. The trap 392T functions in a mannerdescribed with reference to FIG. 7A. The oblique incidence of a cleaningflash on the organic deposits on the mass-sensor 303 can obviate theneed for a heater at the tip of the light guide 392B.

[0060]FIG. 7C shows schematically an alternative optical cleaningconfiguration for removing organic material from a mass-sensor. Acleaning radiation source 390R provides cleaning radiation as a flash oras a timed beam of radiation (for example, a timed beam from a laserlight source) which is directed towards the organic deposits on themass-sensor 303 via a lens or lenses 392L, a radiation-transmissivewindow 392W in the housing 130H, and a mirror 392M which can beoptionally heated by a heater 392HM. The trap 392T is operative asdescribed above.

[0061] Turning now to FIG. 8, there is shown the sensor assembly 300 ofFIG. 7 in which the light guide 392 and the cleaning flash unit 390 isreplaced by a heater 399 connected to a cleaning heater unit 395 vialeads 396 and 398. An optional trap equivalent in function to element392T in FIG. 7 can be included in the sensor assembly of FIG. 8surrounding the heater 399 to collect the sublimate and inhibitsublimate spreading throughout the vacuum chamber.

[0062] Optionally, the heater 399 can be incorporated into the casing202 of the mass-sensor. In this case, it is desirable to not water coolthe sensor casing at the cleaning position in which the sublimate oforganic layers is removed.

[0063] FIGS. 9A-9D are schematic plan views of different embodiments ofrotatable sensor supports which are useful in the practice of theinvention. Positions of a sensor 301 in the deposition zone areindicated by the location of the shield 329, shown in dashed outline,and sensor cleaning positions 392 (the light guide 392 of FIG. 7) arealso depicted in dashed outline.

[0064]FIG. 9A shows a mass-sensor assembly 300A with a rotatable sensorsupport 320A having a single sensor 301 supported thereon.

[0065]FIG. 9B shows a mass-sensor assembly 300B with two sensors 301,302 disposed on a rotatable sensor support 320B.

[0066]FIG. 9C shows a mass-sensor assembly 300C which provides arotatable sensor support 320C adapted to support four sensors 301, 302,303, and 304.

[0067]FIG. 9D depicts a mass-sensor assembly 300D having a circularrotatable sensor support 320D adapted to support an increased number ofsensors, including a sensor 307.

[0068]FIG. 10 is an enlarged section view of the crystal mass-sensorshown in FIG. 5, but having a radiation-absorbing layer 391 preformedover the front electrode 205 of the crystal 204 and over front portionsof the casing 202. The radiation-absorbing layer 391 can be a layer ofradiation-absorbing carbon or other radiation-absorbing material forenhancing removal in whole or in part of accumulated organic layers on asensor disposed on a movable sensor support which can be moved from aposition in the deposition zone 13 v to a cleaning position for removalof organic material by a radiation flash (see FIG. 7), by a radiationexposure (see FIG. 7C) or by a heater (see FIG. 8).

[0069] It will be appreciated that a sensor assembly having one or moresensors disposed on a movable sensor support can be effectivelyincorporated into each one of the vapor deposition stations 130, 140,and 150 of the OLED manufacturing system 100 shown in FIG. 2. Thus, eachof these stations can provide monitoring and control of a vapordeposition rate by a conventional mass-sensor and deposition ratemonitor, and to provide a reusable sensor or reusable sensors bycomplete or partial removal of organic material from mass-loaded sensorsin a cleaning position along a path of motion of a movable sensorsupport.

[0070] The invention has been described in detail with particularreference to certain preferred embodiments thereof, but it will beunderstood that variations and modifications can be effected within thespirit and scope of the invention. PARTS LIST 10 organic light-emittingdevice (OLED) 11 substrate or structure 12 first electrodes 13 organichole-transporting layer (HTL) 13(xN) number N of organichole-transporting layers on mass-sensor 13a organic hole-transportingmaterial 13b level of organic hole-transporting material 13v depositionzone of vapor of organic hole-transporting material 13f organichole-transporting layer being formed 14 organic light-emitting layer(LEL) 15 organic electron-transporting layer (ETL) 16 second electrodes18 encapsulation or cover 100 OLED manufacturing system 102 buffer hub103 unload station 104 transfer hub 105 connector port 106 vacuum pump107 pumping port 108 pressure gauge 110 load station 110C chamber 110Hhousing 111 carrier (for substrates or structures) 130 vapor depositionstation (organic HTL) 130C chamber 130H housing 131 holder and/or maskframe 132 thermally insulative support 134 source 135 heating element(s)140 vapor deposition station (organic LEL) 150 vapor deposition station(organic ETL) 160 vapor deposition station (second electrodes) 170storage station 180 encapsulation station 200 crystal mass-sensor (PRIORART) 202 electrically grounded casing 204 crystal 205 front electrode206 rear electrode 207 connection to rear electrode 209 connection tocasing (and to front electrode) 210 lead 216 input terminal 220deposition rate monitor 222 output terminal 224 lead 226 input terminal230 controller or amplifier 232 output terminal 234 lead 236 inputterminal 240 source (heating) power supply 244 output terminal 245 lead246 output terminal 247 lead 300 mass-sensor assembly with reusablemass-sensor(s) 300A configuration of mass-sensor assembly 300Bconfiguration of mass-sensor assembly 300C configuration of mass-sensorassembly 300D configuration of mass-sensor assembly 301 mass-sensor 302mass-sensor 303 mass-sensor 304 mass-sensor 307 mass-sensor 320 sensorsupport 320A configuration of sensor support 320B configuration ofsensor support 320C configuration of sensor support 320D configurationof sensor support 321 sensor contact 323 lead contact 325 rotator 327seal 329 shield 390 cleaning flash unit 390R cleaning radiation unit 391radiation-absorbing layer 392 light guide 392B light guide providingoblique incidence of cleaning radiation on the sensor 392H heater at tipof light guide 392L lens or lenses 392M mirror 392HM heater for mirror392T trap (for collecting organic sublimate) 392W radiation-transmissivewindow 395 cleaning heater unit 396 lead 398 lead 399 heater

What is claimed is:
 1. A method for depositing an evaporated or sublimedorganic layer onto a structure which will form part of an organiclight-emitting device, comprising the steps of: a) depositing at adeposition zone organic material forming a layer of the organiclight-emitting device; b) providing a movable sensor which, when movedinto the deposition zone and is being coated during the depositing step,provides a signal representing the thickness of the organic materialforming the layer; c) controlling the deposition of the organic materialin response to the signal to control a deposition rate and thickness ofthe organic layer formed on the structure; d) moving the movable sensorfrom the deposition zone to a cleaning position; and e) removing organicmaterial from the movable sensor to permit reuse of the movable sensor.2. A method for depositing an evaporated or sublimed organic layer ontoa structure which will form part of an organic light-emitting device,comprising the steps of: a) depositing at a deposition zone organicmaterial forming a layer of the organic light-emitting device; b)providing at least first and second movable sensors each one of which,when moved into the deposition zone is coated during a deposition oforganic material and provides a signal representing the thickness of theorganic material forming the layer; c) controlling the deposition of theorganic material in response to the signal to control a deposition rateand thickness of the organic layer formed on the structure; d) movingthe first movable sensor after it has been coated with organic materialfrom the deposition zone to a cleaning position; e) moving the secondmovable sensor into the deposition zone; and f) removing organicmaterial from the first movable sensor at the cleaning position topermit reuse of the first movable sensor.
 3. Apparatus for depositing anevaporated or sublimed organic layer onto a structure which will formpart of an organic light-emitting device, comprising: a) a housingdefining a chamber and a pump connected to the chamber for reducing thepressure therein; b) a source for receiving organic material to beevaporated or sublimed and means connected to the source for adjustingthe temperature thereof to control the rate at which the organicmaterial is evaporated or sublimed; c) means for positioning thestructure so that such structure is located spaced from the source in adeposition zone; d) a movable sensor positioned in the deposition zonefor receiving organic material from the source at the same time suchorganic material is deposited onto the structure; e) electrical meansconnected to the sensor and responsive to the thickness of the organicmaterial deposited on the sensor for adjusting the temperature controlmeans to control the rate of deposition and the thickness of the organiclayer formed on the structure; and f) means for moving the sensor out ofthe deposition zone and means for removing in whole or in part organicmaterial deposited on the sensor so that such sensor can be reused inthe deposition zone.
 4. The apparatus of claim 3 wherein the sensor isdisposed on a movable sensor support and the means for removing organicmaterial deposited on the sensor includes flashed radiation or a timedradiation beam directed towards the organic material on the sensor. 5.The apparatus of claim 4 further including a radiation-absorbing layerpreformed on the sensor.
 6. The apparatus of claim 3 wherein the sensoris disposed on a movable sensor support and the means for removingorganic material deposited on the sensor includes a heater positionedproximate the organic material on the sensor.
 7. The apparatus of claim6 further including a heat-absorbing layer preformed on the sensor. 8.Apparatus for depositing an evaporated or sublimed organic layer onto astructure which will form part of an organic light-emitting device,comprising: a) a housing defining a chamber and a pump connected to thechamber for reducing the pressure therein; b) a source for receivingorganic material to be evaporated or sublimed and means connected to thesource for adjusting the temperature thereof to control the rate atwhich the organic material is evaporated or sublimed; c) means forpositioning the structure so that such structure is located spaced fromthe source in a deposition zone; d) a first movable sensor of aplurality of movable sensors positioned in the deposition zone forreceiving organic material from the source at the same time such organicmaterial is deposited onto the structure; e) electrical means connectedto the first movable sensor and responsive to the thickness of theorganic material deposited on the sensor for adjusting the temperaturecontrol means to control the rate of deposition and the thickness of theorganic layer formed on the structure; f) means for moving the firstsensor out of the deposition zone and means for removing in whole or inpart organic material deposited on the sensor so that such sensor can bereused in the deposition zone; and g) means for moving a second movablesensor of the plurality of movable sensors into the deposition zone andelectrical means connected to such second sensor.
 9. The apparatus ofclaim 8 wherein the plurality of sensors are disposed on a movablesensor support and the means for removing organic material deposited onthe first sensor includes flashed radiation or a timed radiation beamdirected towards the organic material on the sensor.
 10. The apparatusof claim 9 further including a radiation-absorbing layer preformed oneach of the plurality of sensors.
 11. The apparatus of claim 8 whereinthe plurality of sensors are disposed on a movable sensor support andthe means for removing organic material deposited on the first sensorincludes a heater positioned proximate the organic material on thesensor.
 12. The apparatus of claim 11 further including a heat-absorbinglayer preformed on each of the plurality of sensors.
 13. The apparatusof claim 9 wherein the movable sensor support is a rotatable sensorsupport.
 14. The apparatus of claim 11 wherein the movable sensorsupport is a rotatable sensor support.
 15. The apparatus of claim 4further including a trap for collecting organic material removed fromthe sensor by the means for removing such organic material.
 16. Theapparatus of claim 15 wherein the trap includes means for cooling. 17.The apparatus of claim 9 further including a trap for collecting organicmaterial removed from the first sensor by the means for removing suchorganic material.
 18. The apparatus of claim 17 wherein the trapincludes means for cooling.